This invention relates to self-service shopping, and in particular to a methodology for improving the security of a self-service shopping system by the use of statistical sampling of shoppers and their purchases.
Self-service shopping systems are desired for their ability to offload service-oriented functions from human labor forces and provide automatic assistance to the shopper for increase in response time, efficiency, throughput, lower cost, and the like. For example, systems in the prior art provide each shopper with a portable bar code scanning device, which is used to scan the bar code located on a product in order to determine the price by accessing a locally stored look-up table and keep a tally list of all items selected for purchase. When the shopper is finished selecting items for purchase and scanning the bar codes on the items, he places the self-scanner into a recess in a stationary (i.e., wall-mounted) cradle, wherein a list of items selected is printed out for a receipt and provided to the shopper. The shopper then brings the list along with the cart of selected items to a clerk for tender of final payment and, possibly, an audit of items selected for purchase in order to ensure that all items selected and placed in the cart were properly scanned. This self-service scenario speeds shoppers through the store quicker than the conventional conveyor belt/cashier environment typical in stores today.
Security in a self-service shopping system as described above is a major concern of retailers. Shoppers who fail to scan the bar code of an item placed in their shopping cart will bring the item home without proper payment, whether such failure to scan the item is intentional or inadvertent. In addition, shoppers may scan an item but place a different (i.e. more expensive) item in their cart. Therefore, some methodology of checking shoppers"" purchases must be implemented in order to satisfy security criteria.
Two goals of a self-checkout system are to increase shopper throughput and to save in labor costs. Ideally, a shopper can scan his items when selected from the shelf and save scanning time at the checkout line. In addition, stores would require less human labor since there is a reduction in the number of cashiers required. However, there is still a requirement to scan some items from a shopper""s cart if a shopper is determined to be audited in order to flag an attempted theft as well as to provide deterrence against pilferage. Thus, some labor is required to scan at least some of the items leaving the store. At one extreme, a system where every shopper has all of his purchase items re-scanned is not feasible since there is no net time savings in such a system (all purchases are scanned by a cashier anyway). There is therefore a need to determine whether a shopper needs to be audited and how many and which items are to be scanned in order to maximize the potential for catching pilferage, provide maximum deterrence against theft, minimize labor costs in checking the shoppers"" scanned items, maintain the increased throughput achieved by the self-checkout system, and avoid the negative inferences inherently made by shoppers whose items are checked by an exit cashier or security guard.
Prior art proposals for checkout security require a cashier to check only certain shoppers, but to scan their entire cart full of goods. This type of system is unsatisfactory for those shoppers who are selected for full checking, since they must wait for the entire cart to be re-scanned (thus defeating the purpose of the self-checkout system), suffer potential embarrassment at being singled out by the store for security checking, etc. Thus, an entirely new methodology is needed to supplant this security checking system.
The present invention proposes the implementation of a statistical basis for use in a self-scanning checkout system for determining whether a shopper or customer should be audited and how many items to check in a shopper""s shopping cart for incorrect or missing scans as well as which particular or types of items to check to determine if they were properly scanned. In the present invention, a fraction of the shoppers, depending upon an algorithm, will be checked by a cashier or security guard, but only a limited and select number of items will be checked for each shopper. The present methodology determines how many items to check for a given shopper as well as which particular items to check for that shopper. The following factors may be considered, alone or in varying combinations, in determining the number or type of items to check for a particular shopping transaction: shopper frequency (the number of times the shopper has visited that store), queue length (the length of the checkout line at that time); prior history (check more items if the shopper has had errors in the past, check less items if the shopper has had no errors in the past), store location (check more items in stores located in areas with a high risk of pilferage); time of day, day of week, date of year (determine if pilferage more likely at certain times of day or year); number of times items are returned to shelf during shopping; dwell time between scans, and other factors.
In a method aspect of the present invention, provided is a method for use in a self-service shopping checkout system wherein a shopper is provided with a self-scanning terminal for the scanning of the bar code of an item selected for purchase prior to depositing the item into a shopping cart, and wherein a list of items self-scanned by the shopper is compiled and made available to a cashier for surveillance and payment purposes. The method performs a security check to determine if the shopper did not likely fail to scan an item prior to depositing the item into the shopping cart. The method comprises the steps of determining, as a function of a plurality of input criteria, whether a shopper should be audited and the number of items n to be scanned, selecting from the shopper""s cart of items presented for purchase n items to be scanned, scanning a bar code located on each of said n items selected for scanning, allowing the shopping transaction if each item selected for scanning is present on the list of self-scanned items compiled by the shopper, and disallowing the shopping transaction if any item selected for scanning is not present on the list of self-scanned items compiled by the shopper. The number of items n is determined as a function of the criteria mentioned above. The method further comprises the steps of selecting items at random system checks and determining whether more items are needed to be checked until statistical significance is achieved.
In a systems aspect, the present invention comprises several alternative embodiments. In each embodiment, a self-service shopping checkout system comprises a plurality of portable self-checkout devices, wherein each of the self-checkout devices is to be used by a customer to scan a bar code located on an item to be purchased so as to record therein a list of such items to be purchased. In one embodiment, a stationary dispenser unit is used for the releasable containment of said plurality of portable self-checkout devices and transmission of data stored in the devices by wireline to a host computer for processing; and a plurality of point-of-sale terminals using the host processing to check out the customer. In another embodiment, the portable device contains a wireless transceiver for transmitting the data stored in the device directly to the host computer in lieu of storing the data in the device and using the dispenser to transmit the stored data to the computer. In still another embodiment, the portable device is a dumb terminal for collecting and storing the shopping data which may be used in conjunction with a kiosk to determine the prices and cost of items selected for purchase. The kiosk contains a display and a rack for receiving the dumb terminal to communicate with the host computer by wireline or a wireless link. In response to customer inputs, the desired information is presented on the display. Alternatively, the customer may place the dumb terminal in a cradle at the checkout stand. The cradle loads the data in the dumb terminal into the host computer for processing and check out of the customer.
In the present system, each of the portable self-checkout devices comprises bar code scanning means for scanning and decoding a bar code located on an item to be purchased, means for compiling a list of items scanned by said customer, and a data output port for allowing transfer of said scanned item list to an associated data port located in a dispenser external to said portable device or by wireless link directly to a host computer for processing the shopper""s items selected for purchase. In one embodiment, the dispenser unit of the system comprises a plurality of device containment slots, each of said slots being configured for releasable containment of a mating self-scanning device, each of said slots having associated therewith a data input port suitable for mating with a data output port located on a portable self-checkout device, and a printer for printing a tally list of items scanned for purchase by said shopper, said tally list being supplied by a self-checkout device after said self-checkout device is returned to a device containment slot after being used by a shopper, said tally list further comprising a bar code encoded with said items scanned by said shopper, a unique identification record associated with said shopper, and the number of items scanned by said shopper. Each of the point-of-sale terminals in the present system comprises bar code reading means for reading said two-dimensional bar code from a tally list presented to a cashier operating said point-of-sale terminal, said bar code reading means providing as output data signals representing said items scanned by said shopper, a unique identification record associated with said shopper, and the number of items scanned by said shopper. Each of the point-of-sale terminals in the present system comprises bar code reading means for reading said two-dimensional bar code from a tally list presented to a cashier operating said point-of-sale terminal, said bar code reading means providing as output data signals representing said items scanned by said shopper, said unique identification record associated with said shopper, and said number of items scanned by said shopper; said bar code reading means also configured so as to scan select items presented for checking by said cashier; means for determining, as a function of said number of items scanned by said customer and an internally stored check number unique to said customer, the number of items n to be scanned by the cashier; means for comparing the identity of the items scanned by said cashier with the list of items scanned by said customer; means for allowing the shopping transaction if each item selected for scanning by the cashier is present on the list of self-scanned items compiled by the shopper; and means for disallowing the shopping transaction if any item selected for scanning by the cashier is not present on the list of self-scanned items compiled by the shopper.
The present invention may be further enhanced using other auditing factors as a basis for statistical techniques for self-check out. Among the audit factors for such self-checkout are shopper audit history, loyalty of shoppers, regional differences and other factors which attempt to model the real world to obtain the minimum checkout loss for a shopper. After a determination whether a shopper should be audited and, if so, how many items should be selected for audit, a shopping transaction is allowed according to a statistical decision if the minimum check-out loss for the transaction is less than a threshold defined by a loss function L(c) and (p), where L(c) is the expected inventory loss associated with the shopper and (p) is the probability of performing an audit on the shopper.